In video coding systems, spatial and temporal redundancy is exploited using spatial and temporal prediction to reduce the information to be transmitted. The spatial and temporal prediction utilizes decoded pixels from the same picture and reference pictures respectively to form prediction for current pixels to be coded. The transmission of motion vectors for temporal prediction may require a noticeable portion of the compressed video data, particularly in low-bitrate applications. In order to reduce the bitrate associated with motion vectors, a technique called Motion Vector Prediction (MVP) has been used in the field of video coding. The MVP technique exploits the statistic redundancy among neighboring motion vectors spatially and temporally.
In High Efficiency Video Coding (HEVC), techniques to improve the efficiency of MVP are explored. Both spatial and temporal Motion Vector Predictors are used to increase the possibility of obtaining a predictor to achieve better performance. However, when a derived MVP is the same as a previously derived MVP, the currently derived MVP does not offer any potential to further improve the coding efficiency. Accordingly, in HM-3.0 (HEVC Test Model version 3.0), the MVP process incorporates redundancy checking during spatial and temporal MVP derivation. While the redundancy checking adopted by HM-3.0 shows certain efficiency improvement, it is desirable to extend redundancy check to further improve system performance.